D2D (Device to Device) communication refers to a communication between an electronic device and another electronic device. As a broader definition, D2D communication refers to a wireless or wired communication between electronic devices, or to a communication between a user-controlled device and a machine. However, recently, D2D communication has generally been defined as a wireless communication between an electronic device and another electronic device, which is performed without any human intervention.
When the concept of D2D communication was first adopted in the early 1990's, D2D communication was merely understood and recognized as the concept of remotely controlled communication or telematics, and the related market was also limited to such concept. However, over the past few years, D2D communication has been under development at a remarkable rate and has now evolved to a market drawing national and worldwide attention. Most particularly, the D2D communication has greatly influenced diverse fields including Fleet Management, remote monitoring of devices and equipments, smart meter for measuring the operation time of a construction equipment installation and for automatically measuring the usage amount of heat or electricity in an applied market related to the Point of Sales (POS) and security. The D2D communication that is to be used in the future is expected to be used and applied for a wider scope of usage in association with the conventional mobile communication and high speed wireless internet or low power communication solutions, such as Wi-Fi and Zigbee, thereby becoming the basis for expanding its market domain to the B2C market, and not being limited only to the B2B market.
In the age of D2D communication, all types of machines (or devices) equipped with a SIM (Subscriber Identity Module) card may perform data reception and transmission, thereby being capable of being remotely controlled and managed. For example, being applied to an extended range of devices and equipments, such as cars, trucks, trains, containers, vending machines, gas tanks, and so on, the D2D communication technology may be applied to an enormous range of application. However, research of the D2D communication method including a base station and D2D user equipments is still is a state of requiring further development.